The present invention relates to a tabletting machine, i.e., to a machine for compressing pulverulent and similar materials to form tablets (e.g., medication, candy or the like).
The nature of the material handled in tabletting machines makes it impossible to avoid the evolution of powdery dust during admission of the material to be acted upon, as well as during pressing and subsequent ejection of the finished tablets. Those skilled in the art will know the manifold problems arising from this dust evolution. These problems have led to the provision of suction equipment by means of which the dust is to be aspirated and removed.
Generally speaking, this measure is satisfactory in that it alleviates many of the dust-related problems. However, one problem which even this measure does not adequately solve is the deposition of the fine dust on the shafts of the plungers (i.e., the elements which perform the compressing) which reciprocate in plunger guides. During this reciprocation the dust is then carried into the guides and into contact with their guide surfaces which tightly surround the plunger shafts. It is readily evident that the dust, once it reaches this position, will during succeeding reciprocations of the plungers act as an abrasive that wears away the cooperating surfaces of the plunger shafts and plunger guides. Over a period of time this wear becomes so pronounced that the plungers are no longer accurately guided. In addition, the presence of the dust in the plunger guides severely reduces the ease of reciprocation, to such an extent that the plungers--urged by cams or other motion-imparting equipment to recriprocate but seized in the guides due to the presence of the dust--may become damaged.